As techniques for quantizing an LSP parameter, which is one of coefficients transformable to linear predictive coefficients, methods such as vector quantization are known (see, for example, Non-patent literature 1).
By the way, a parameter η has been proposed by the inventor though it is not publicly known. This parameter η is a shape parameter that defines probability distribution to which coding targets of arithmetic coding belong, in such a coding system for performing arithmetic coding of quantized values of coefficients in a frequency domain, utilizing a linear prediction envelope as is used in the 3GPP EVS (Enhanced Voice Services) standard. The parameter η has relevance to distribution of the coding targets, and it is possible to perform efficient coding and decoding by appropriately setting the parameter η.
Further, the parameter η can be an indicator indicating characteristics of a time-series signal. Therefore, when the parameter η is appropriately used, it is possible to efficiently perform coding and decoding coefficients transformable to linear predictive coefficients such as LSP parameters.